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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org, "Hans Verkuil" <hans.verkuil@cisco.com>,
        "Mauro Carvalho Chehab" <mchehab@s-opensource.com>,
        "Sakari Ailus" <sakari.ailus@linux.intel.com>
Date:   Wed, 28 Feb 2018 15:20:18 +0000
Message-ID: <lsq.1519831218.80070526@decadent.org.uk>
Subject: [PATCH 3.16 251/254] media: v4l2-compat-ioctl32.c: don't copy 
 back the result for certain errors
In-Reply-To: <lsq.1519831217.271785318@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
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3.16.55-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Hans Verkuil <hans.verkuil@cisco.com>

commit d83a8243aaefe62ace433e4384a4f077bed86acb upstream.

Some ioctls need to copy back the result even if the ioctl returned
an error. However, don't do this for the error code -ENOTTY.
It makes no sense in that cases.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 drivers/media/v4l2-core/v4l2-compat-ioctl32.c | 3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
+++ b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
@@ -933,6 +933,9 @@ static long do_video_ioctl(struct file *
 		set_fs(old_fs);
 	}
 
+	if (err == -ENOTTY)
+		return err;
+
 	/* Special case: even after an error we need to put the
 	   results back for these ioctls since the error_idx will
 	   contain information on which control failed. */